1. Field of the Invention
The present invention relates to a method and an apparatus for dynamic image region extraction capable of extracting an image of a significant moving object in a dynamic image.
2. Description of the Background Art
In general, in a field of an image composition, the following methods are known for an extraction of a dynamic image region to be used in producing a composite image in which the images of specific significant moving objects such as persons and flowers are cut out from an ordinary image and arranged at appropriate positions.
One of the conventionally known methods is a region extraction method using a chromaky in which a special background image such as the blue background is used as an original image for the extraction.
However, this region extraction method using a chromaky has been associated with a problem that it is necessary to prepare the special background at a time of image taking, so that it is not applicable to the images obtained by the ordinary image taking procedure.
Another one of the conventionally known methods is a region extraction method using a video matte in which the boundary of the region to be extracted is inputted manually in units of picture elements on the ordinary image. This method is capable of extracting the significant region accurately in principle.
However, this region extraction method using a video matte has been associated with a problem that because it basically depends upon the manual operation by an operator, it requires considerable amounts of work, time, and skill in order for the operator to achieve the accurate input of the boundary, one picture element by one picture element, manually.
There is also a proposition for an apparatus for a region extraction in a static image such as that disclosed in Japanese Patent Application No. 1-314384, a schematic configuration of which is shown in FIG. 1.
In this region extraction apparatus of FIG. 1, a boundary of a significant region determined on a basis of the original image is manually inputted in a form of an outline figure through an outline figure input unit 1, and a thinning is applied to a rough boundary image signal 1a outputted by the outline figure input unit 1 at an edge information based thinning unit 2. Here, in the thinning of the outline figure, an edge image signal 3a obtained by an edge extraction unit with masking 3 is utilized by the edge information based thinning unit 2 such that the thinning is applied to the portions having small edge information values (edge components) with greater priority. Then, a thinned image signal 2a outputted by the edge information based thinning unit 2 is painted out by a paint out unit 4 to obtain a region image signal 4a, which is then multiplied with the input image signal 5a so as to obtain the output image signal 6a containing only the image of the significant region.
Although this region extraction apparatus of FIG. 1 has an advantage that the significant region can be extracted easily by simply inputting an outline figure, it has been applicable only to the static image, so that the development of this type of a region extraction apparatus capable of dealing with a dynamic image has been eagerly awaited.